How can a Philips AC-DC transform make so much noise?

serch for the text "acoustic noise" read the rightmost column

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Thanks. And so, I have nothing to do, do I? This is the only one which I get such a problem with.

It's possible that it hasn't enough load on it and is cycling on/off. Some chargers are designed to do this if it does not detect a proper load due to the possibility of a bad battery or doing battery detection cycles.

And some, like I said, are just plain noisy with no load on them because they are designed for the battery load which is much greater than just sitting idle. Normally, there is a load in there to help this out how ever, its been a big thing about wall adapters sucking power while your device isn't plugged in. Vampire Wallworts is a slang name for that. So the noise you hear could also be the detection circuit operating and looking for a load to switch and it could be on the edge of a trigger.

er

m

Okay, I just plugged the shaver in, and put my ear next to the transformer, and, actually, the noise is really even more perceptible when the saver is plugged. This doubles the noise.

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have you contacted Philips' customer support?

It does not look like some malfunction, simply some excessive noise, and sure they'll tell me that this is normal.

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If it's annoying to the point where it's depriving you of sleep, then
If it were me I'd let them know about it.

It's your life though... do what you like.

But you know, their servicing is always the same. That's the problem.

I can deactivate it, but, clearly, it is annoying.

Well, you've put in time and effort to post here. Why not put in time and effort to contact Philips, as John mentioned? Who knows - they might have a product recall on the thing, or a simple fix. In any event, it couldn't hurt so you might as well try it.

For a possible "quick fix", try putting a piece of foam rubber or a terry cloth towel under the thing to see if that damps the sound.

Ed

Thanks. Done. I'll let you know.

It is on an `electrical extension' (I don't know if this is how you call this) that I always disconnect, except when I want to charge the shaver. The problem is that if I need it tomorrow, I cannot charge it in my bedroom the night. Or, if I dare do this, I won't sleep(!), but will be shaved tomorrow. Funny.

Does the shaver actually plug into the charger via electrical contacts, or is it inductively coupled? If the latter, there are coils of wire in the charger and shaver that form the primary and secondary windings of a transformer. The alternating magnetic field in the charger primary induces a current in the shaver secondary, but unlike a conventional transformer where the windings are (hopefully) firmly attached to each other and an iron core, here the shaver is more-or-less free to move.

Try pressing pressing and holding the shaver into the charger to see if that reduces the sound by restricting motion. If that quiets it down, you might rig up something like a heavy rubber band to hold them together.

Another possibility is that the coils in the charger and/or shaver are not securely mounted. That would fit with the observation that you hear sound even when the shaver is not plugged in. If you can open the charger (disconnected from the mains!) and get to the coil, you may be able to anchor it with glue.

Best regards,

Bob Masta DAQARTA v5.10 Data AcQuisition And Real-Time Analysis

Scope, Spectrum, Spectrogram, Sound Level Meter Frequency Counter, FREE Signal Generator Pitch Track, Pitch-to-MIDI DaqMusic - FREE MUSIC, Forever! (Some assembly required) Science (and fun!) with your sound card!

Thanks for this answer. Actually, it is not charged by inductive couple. There are simply two pieces of a conductive material at the bottom of the dock, and plugging the shaver into the dock results in a contact between the shaver and the charger, which therefore charges it. I contacted Philips, and this is definitely not normal, they said. I should get another one later. If I have some spare time, it is possible for me to open the transformer, and check if everything is right, this one being disconnected from the mains. Can I also open the transformer? Thanks.

Are you saying that the transformer is a separate unit from the charger? Whichever the situation, if the noise is coming from the unit with the transformer, it's possible that the windings are loose on the core, and might be fixed by a little glue. As far as opening the case goes, many of these are welded plastic with no convenient screws to remove. I have had luck in the past cutting open a wall-wart and re-glueing it later... worked fine, but it sure looked ugly!

Best regards,

Bob Masta DAQARTA v5.10 Data AcQuisition And Real-Time Analysis

Scope, Spectrum, Spectrogram, Sound Level Meter Frequency Counter, FREE Signal Generator Pitch Track, Pitch-to-MIDI DaqMusic - FREE MUSIC, Forever! (Some assembly required) Science (and fun!) with your sound card!

The charger is connected to the transformer with a wire, simply. I plug the shaver in the charger.

I'll know the problem thanks to Philips. Thanks. :-)